• The Journal of the Acoustical Society of Korea
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• v.30 no.1
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• pp.56-62
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• 2011

In the present study, the phase velocities of guided ultrasonic waves such as the first arriving signal (FAS) and the slow guided wave (SGW) propagating along the long axis on the 12 tubular cortical bone samples in vitro were measured and their correlations with the cortical thickness were investigated. The phase velocities of the FAS and the SGW were measured by using the axial transmission method in air with a pair of unfocused ultrasonic transducers with a diameter of 12.7 mm and a center frequency of 200 kHz. The phase velocity of the FAS measured at 200 kHz exhibited a very high negative correlation with the cortical thickness and that of the SGW arriving after the FAS showed a high positive correlation with the cortical thickness. The simple and multiple linear regression models with the phase velocities of the FAS and the SGW as independent variables and the cortical thickness as a dependent variable revealed that the coefficient of determination of the multiple linear regression model was higher than those of the simple linear regression models. The phase velocities of the FAS and the SGW measured at 200 kHz on the 12 tubular cortical bone samples were, respectively, consistent with those of the S0 and the A0 Lamb modes calculated at 200 kHz on the cortical bone plate.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.2
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• pp.100-104
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• 2023

Autogenous bone grafts from the mandibular ramus are a known source of inadequate bone volume scenarios of the residual alveolar ridge. However, the conventional block-type harvesting technique cannot prevent bone marrow invasion, which can cause postoperative complications such as pain, swelling, and inferior alveolar nerve injury. This study aims to suggest a complication-free harvesting technique and present the results of bone grafting and donor sites. One patient received two dental implants with a complication-free harvesting technique that involves creation of ditching holes with a 1 mm round bur. Sagittal, coronal, and axial osteotomies produced grid-type cortical squares using a micro-saw and a round bur to confirm the cortical thickness. The grid-type cortical bone was harvested from the occlusal aspect, and the harvesting was extended through an additional osteotomy on the exposed and remaining cortical bone to prevent bone marrow invasion. The patient did not suffer postoperative severe pain, swelling, or numbness. After 15 months, the harvested site exhibited new cortical bone lining, and the grafted area had healed to a cortico-cancellous complex with functional loading of the implants. Our technique, grid-type cortical bone harvesting without bone marrow invasion, allowed application of autogenous bone without bone marrow invasion to achieve acceptable bone healing of the dental implants and to regenerate the harvested cortical bone.

• The Journal of the Acoustical Society of Korea
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• v.32 no.2
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• pp.181-189
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• 2013

The purpose of the present study is to investigate the effect of cortical bone on acoustic properties of trabecular bone, such as speed of sound (SOS) and normalized broadband ultrasound attenuation (nBUA), in bovine femur in vitro. Twelve trabecular bone samples and three cortical bone plates with thicknesses of 1.00, 1.47, and 2.00 mm were extracted from the proximal end of two bovine femurs. The correlations between acoustic properties and trabecular apparent bone density were also examined before and after attaching a cortical bone plate to the trabecular bone samples. SOS increased linearly with increasing thickness of the cortical plate attached to one side of ultrasonic incidence of the trabecular bone samples, whereas nBUA showed a nonlinear dependence on the thickness of the cortical plate. All the SOS (r = 0.95-0.97) and nBUA (r = 0.53-0.73) measurements with and without the cortical bone plate with various thicknesses were found to exhibit high correlations with the trabecular apparent bone density. These results imply that the acoustic properties measured in the femur with lateral cortical layers in vitro can be useful indices for the prediction of trabecular bone mineral density.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.4
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• pp.275-278
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• 1998

Recently, the clinical applications of the autogenous cancellous bone from the proximal tibial metaphysis show satisfactory results in the repair of maxillofacial bony defect or deformity. The proximal tibia has the potential to yield viable cancellous bone with a minimum of morbidity. The purpose of this study was to investigate the regeneration of a full thickness proximal tibial bone defect with covering or uncovering of cortical bone. The follow-up periods were 4, 8, and 12 weeks. Bone defect of right side was uncovered and left side was covered with cortical bone. In the experimental group (uncovered cortical bone) at 12 weeks, the inside of defect was filled to normal marrow tissue. The cortical bone defect was united of inner, outer callus at 4, 8 weeks in both study group. At 12 weeks, the cortical bone defect was remodeled and invaded by osteoclast (giant cell) in experimental group. In the experimental specimen at 12 weeks, the regenerating tissue of bone defect was not differ from the control group.

• International Journal of Oral Biology
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• v.36 no.2
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• pp.65-70
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• 2011

Recently, mini-implant is popular in the orthodontic treatment due to its simplicity and convenient surgical procedure. The objective of this study is to provide the anatomical guideline for mini-implant placement by analysing the cortical bone thickness in Korean. Hemi-sections of sixteen maxillae and twenty-two mandibles with normal teeth were used. Interdental areas between the 1st premolar and the 2nd premolar (Group 1), the 2nd premolar and the 1st molar (Gruop 2), and the 1st molar and the 2nd molar (Group 3) were sectioned and then scanned. After setting the axis of teeth, the cortical bone thickness was measured at the distance of 2 mm, 4mm, 6 mm, and 8 mm from alveolar crest. The mean thickness of cortical bone in the maxilla according to distance from alveolar crest was $1.30\;{\pm}\;0.63\; mm$ (2 mm), $1.49\;{\pm}\;0.62\; mm$ (4mm), $1.72\;{\pm}\;0.64\; mm$ (6mm), and $1.90\;{\pm}\;0.90\; mm$ (8 mm) at the buccal side and $1.33\;{\pm}\;0.47 \;mm$, $1.31\;{\pm}\;0.45\; mm$, $1.37\;{\pm}\;0.55\; mm$, and $1.39\;{\pm}\;0.58 \;mm$ at the palatal side. In the mandible, that was $3.14\;{\pm}\;1.71 \;mm$, $4.31\;{\pm}\;2.22 \;mm$, $4.23\;{\pm}\;1.94 \;mm$, and $4.30\;{\pm}\;1.57\; mm$ at the buccal side and $1.98\;{\pm}\;0.88 \;mm$, $2.79\;{\pm}\;1.01\; mm$, $3.35\;{\pm}\;1.27$ mm, and $3.93\;{\pm}\;1.38\; mm$ at the lingual side. The buccal cortical bone thickness in the maxilla was decreased from Group 1 to Group 3, while the thickness of palatal side was no change. In the mandible, it did not show a tendency at the buccal side and it was decreased from Group 1 to Group 3 without significant difference at the lingual side. Therefore, the buccal side of the Group 1 and Group 2 in both the maxilla and mandible seems to be the most appropriate site for a mini-implant placement with taking the stability and retention.

• Journal of Periodontal and Implant Science
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• v.31 no.3
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• pp.581-595
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• 2001

In performing implant procedures in the anterior portion of the maxilla, many difficulties exist because of anatomical reasons, such as the proximity of the nasal floor, lateral extension of the incisive canal, and labial concavity. On the other hand, in the posterior region of the maxilla, there is often insufficient recipient bone between the maxillary sinus and alveolar ridge due to alveolar ridge resorption and pneumatization of the maxillary sinus. In order to perform implants in such regions, ridge augmentation procedures such as onlay bone graft, guided bone regeneration, and maxillary sinus grafting are performed. In studies of Caucasians, use of autograft from mandibular symphysis has been reported to be highly successful in maxillary sinus grafting. However, in a clinical study of Koreans, autograft of mandibular symphysis has been reported to have significantly low success rate. It has been hypothesized that this is because of insufficient cancellous bone due to thick cortical bone. In order to test this hypothesis, bone quality and morphology of Koreans can be compared with those of Caucasians. In this study, the bone density and morphology of the cortical bone and cancellous bone in the mandibular symphysis of 35 Korean cadavers were evaluated. The following results were obtained: 1. In terms of bone density, type I, type II, and type III consisted of 1.4%(3/213), 72.3%(154/213), and 26.3%(56/213) of the cross-sectioned specimens, respectively. In general, the bone density tended to change from type II to type III, as cross-sectioned specimens were evaluated from the midline to the canine. Type IV wasn't observed in this study. 2. The distance between the root apex and the lower border of the cancellous bone was 18.34mm-20.59mm. Considering that the bone has to be cut 5mm below the root apex during the procedure, autografts with about 15mm of vertical thickness can be obtained. 3. The thickness of cortical bone on the labial side increased from the root apex to the lower border of the mandible. The average values ranged from 1.43mm to 2.36mm. 4. The labio-lingual thickness of cancellous bone ranged from 3.43mm to 6.51mm. The thickness tended to increase from the apex to the lower border of the mandible and decrease around the lower border of cancellous bone. From the above results, the anatomic factors of the mandibular symphysis (bone density, thickness, quantity and length of the cortical bone and cancellous bone) didn't show any difference from Caucasians, and it cannot be viewed as the cause of failure in autografts in the maxillary sinus for implants.

• The korean journal of orthodontics
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• v.43 no.2
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• pp.83-95
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• 2013

Objective: To evaluate the changes in cortical bone thickness, alveolar bone height, and the incidence of dehiscence and fenestration in the surrounding alveolar bone of posterior teeth after rapid maxillary expansion (RME) treatment using cone-beam computed tomography (CBCT). Methods: The CBCT records of 20 subjects (9 boys, mean age: $13.97{\pm}1.17$ years; 11 girls, mean age: $13.53{\pm}2.12$ year) that underwent RME were selected from the archives. CBCT scans had been taken before (T1) and after (T2) the RME. Moreover, 10 of the subjects had 6-month retention (T3) records. We used the CBCT data to evaluate the buccal and palatal aspects of the canines, first and second premolars, and the first molars at 3 vertical levels. The cortical bone thickness and alveolar bone height at T1 and T2 were evaluated with the paired-samples t-test or the Wilcoxon signed-rank test. Repeated measure ANOVA or the Friedman test was used to evaluate the statistical significance at T1, T2, and T3. Statistical significance was set at p < 0.05. Results: The buccal cortical bone thickness decreased gradually from baseline to the end of the retention period. After expansion, the buccal alveolar bone height was reduced significantly; however, this change was not statistically significant after the 6-month retention period. During the course of the treatment, the incidence of dehiscence and fenestration increased and decreased, respectively. Conclusions: RME may have detrimental effects on the supporting alveolar bone, since the thickness and height of the buccal alveolar bone decreased during the retention period.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.5
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• pp.519-526
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• 2000

Osteoporosis has recently been recognized as a major health problem in the elderly population. The disorder is manifested as a loss of bone mass accompanied by structural alteration of bone and increased incidence of fracture. Mandible also may be affected. So, I evaluated panoramic views of 66 postmenopausal women for finding the possibility of useful diagnostic mandibular parmeters of osteoporosis. To know the correlationship between skeleton and mandible, the average of the bone mineral density of lumbar from 2nd to 4th by the dual energy X-ray absorptiometry(DEXA, LUNAR DPZ. USA), and age and mandibular parameters, that is, the number of residual teeth, alveolar ridge resorption ratio, panoramic mandibular index (PMI), mandibular cortical width (MCW), angular cortical thickness (ACT), ramus cortical thickness (RCT), morphology of mandibular inferior cortical (MIC) were compared. And I divided the all tested women to the osteoporotic group and non-osteoporotic group by the use of T-score -2.0, which was derived from skeletal bone mineral density (BMD). To find the correlationship of the each group with mandibular parameters, t-test and discriminant analysis were done. The results of the t-test were that all parameters were highly related with 2 groups (p<0.05). Especially ACT, MIC, age have had even higher correlationship than others (p<0.001). The results of the discriminant analysis by the use of these ACT, MIC and age were that the discriminant function was Z = -2.973+(-1.447)$\times$(ACT)+1.131$\times$(MIC score)+(0.052)$\times$(age), the cutting score was 0.257 and the classification accuracy was 84.8%. Therefore I suggest that the consideration of the angular cortical thickness (ACT), the age of patient and the morphology of mandibular inferior cortical(MIC) may help find the osteoporosis.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.250-259
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• 2011

The aim of this study was to suggest a design for an orthodontic miniscrew which may work most favorably in the thin cortical bone of the adolescent. In this study, orthodontic miniscrews with different diameters, lengths, and body types were manufactured and implanted in two artificial bone samples with different cortical bone thickness. Maximum insertion torque, maximum removal torque, and lateral alteration torque were measured. As a result, the bone quality, body type, diameter, and the length all had their effects on the maximum insertion torque, maximum removal torque, and lateral alteration torque. Cortical bone thickness was the most important factor. In initial stability, conical types showed better results than cylindrical types. Increase in the diameter had favorable effects in achieving mechanical stability. Increase in the length did not have as much influence as the other factors did on the initial stability, but there was a statistically significant difference between screws of 6 mm and 8 mm lengths(p<0.05). In conclusion, the conical type screw with a diameter of 1.8 mm is most favorable in the thin cortical bone of the adolescent. In terms of length, the 8 mm screw is expected to perform better than the 6 mm screw.

• Imaging Science in Dentistry
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• v.36 no.4
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• pp.183-188
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• 2006

Purpose: The purpose of this research was to study bone changes after bilateral sagittal split osteotomy through fractal analysis and measurement of mandibular cortical thickness. Materials and Methods: This study included twenty-two prognathic patients who underwent bilateral sagittal split osteotomy. Panoramic radiographs of these patients were taken immediately before operation and at 1 month, 6 months, and 12 months postoperatively. The fractal dimension was measured by the box-counting method in the region of interest centered on both the basal and interdental bones between the first and second mandibular molars. Measurements of mandibular cortical thickness were taken both in the area between the first and second mandibular molars and at the osteotomy site. Changes of fractal dimension and cortical thickness over four stages were statistically analyzed. Results: The fractal dimension of the mandibular basal bone before surgery and after 1 month, 6 months and 12 months were $1.4099{\pm}0.0657,\;1.382{\pm}0.0595,\;1.2995{\pm}0.0949,\;and\;1.4166{\pm}0.0676$, respectively (Repeated-measures ANOVA, P<0.001). However, no statistically significant differences were noted in interdental fractal dimensions among the four stages. Mandibular cortical thickness between the first and second mandibular molars before operation and after 1 month, 6 months and 12 months was $3.74{\pm}0.48mm,\;3.63{\pm}0.47mm,\;3.41{\pm}0.61mm\;and\;3.55{\pm}0.66mm$ (P<0.01), respectively. Mandibular cortical thickness at the osteotomy site at each of the four stages was $3.22{\pm}0.44mm,\;2.87{\pm}0.59mm,\;2.37{\pm}0.61mm\;and\;2.64{\pm}0.62mm$, respectively (P<0.001). Conclusion: This study suggests that the mandibular tissue continued decreasing for 6 months postoperatively and then increased over the subsequent 6 months.